You can also bury the fuse array inside the chip. So in addition to the microscope, you will also have to non-destructively etch or mill the chip to expose the

You can also bury the fuse array inside the chip. So in addition to the microscope, you will also have to non-destructively etch or mill the chip to expose the fuses. This also renders the chip non-functional, so if the secret is unique per chip, then the leaked secret can't be used to bootstrap to other secrets on the die.